Syntheses and ESR spectra of radicals produced in the thermal decomposition of tetraarylsuccinonitriles

Tetraarylsuccinonitriles 2a–e were synthesized via oxidative dimerization of diarylacetonitriles 1a–e in basic media. The thermal decomposition of 2 results in two identical cyanodiarylmethyl radicals 3. Both 1H and 13C NMR analyses of 1a–e and 2a–e and ESR spectra of 3a–e are presented and discussed. The results of ESR measurements provide a plausible explanation for the different reactivity of cyanodiarylmethyl radicals 3a–e in free radical polymerization.